Ontogeny of proopiomelanocortin (POMC) gene expression in the intermediate lobe of the rat pituitary gland.
The ontogeny of proopiomelanocortin (POMC) gene expression in the intermediate lobe of the pituitary was studied in rats of both sexes using quantitative in situ hybridization performed on fixed pituitary sections. Electron microscopic studies revealed in the adult animal the hybridization signal was found in all the secretory cells of the intermediate lobe and only in the POMC cells in the anterior lobe, thus indicating the specificity of the technique used. Hybridization signal was first detected on day 15 of gestation and progressively increased during foetal life. After birth, POMC and mRNA levels markedly increased so that, in one-day old animals, they were 4.5-fold higher than at the end of gestation. Thereafter, mRNA concentrations steadily increased to reach a plateau at 60 days of age in both sexes. No sexual dimorphism was observed at any ages. The results indicate that the development of intermediate lobe cells occurs mostly after birth. They are consistent with previous results indicating a 200-fold increase in the levels of POMC-derived peptides from birth to adulthood.
Tong
Y
Y
CHUL Research Center, Laval University Medical Center, Quebec, Canada.
Pelletier
G
G
D000818:Animals; D001345:Autoradiography; D015342:DNA Probes; D005091:Exons; D005260:Female; D005865:Gestational Age; D008297:Male; D009693:Nucleic Acid Hybridization; D010902:Pituitary Gland / Q000196:embryology* / Q000378:metabolism; D010957:Plasmids; D011247:Pregnancy; D011333:Pro-Opiomelanocortin / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013462:Sulfur Radioisotopes
D015342:DNA Probes; D012333:RNA, Messenger; D013462:Sulfur Radioisotopes; D011333:Pro-Opiomelanocortin